1. Field of the Invention
The present invention relates to a power hammer adapted for to drive nails into objects to be fastened together and, more specifically, to a hammer head assembly for power hammer.
2. Description of the Related Art
FIG. 11 shows a hammer head assembly for power hammer according to the prior art. According to this design, the hammer head assembly comprises a hollow mounting base 8, the mounting base 8 having an outer thread 81 threaded into the corresponding mounting hole of the power hammer and an axially extended stepped center through hole 82, a nail holder 7 axially slidably mounted in the axially extended stepped center through hole 82 of the mounting base 8, the nail holder 7 having a bottom hole 71 adapted to receive a nail 9 having a head 91, a compression spring 811 mounted inside the mounting base 8 and imparting a downward pressure to the nail holder 7, a magnet 72 provided inside the nail holder 7 and adapted to attract the nail 9 loaded in the bottom hole 71 of the nail holder 7, and a hammering rod 73 inserted into the nail holder 7 and adapted to drive the loaded nail 9 into the workpiece. This design of hammer head assembly is practical for driving regular nails into the workpiece, however it is not suitable for driving washer faced screw nails.
The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a hammer head assembly for power hammer, which is suitable for driving any of a variety of nails. It is another object of the present invention to provide a hammer head assembly for power hammer, which positively holds the loaded nail in position for driving. To achieve these and other objects of the present invention, the hammer head assembly comprises an externally threaded mounting base fastened to a mounting hole of the power hammer, the mounting base having an axially extended center through hole extended through top and bottom sides thereof; a nail holder axially slidably inserted into the axially extended center through hole of the mounting base from the bottom side of the mounting base, the nail holder having a longitudinal sliding groove in the periphery thereof, an axially extended center through hole, and a bottom skirt extended around a bottom end of the axially extended center through hole of the nail holder, the bottom skirt having a vertical peripheral wall defining a receiving open chamber adapted to hold the washer of a washer faced screw nail; a spring member provided inside the mounting base and adapted to force the nail holder downwardly out of the mounting base; a hammering rod inserted into the axially extended center through hole of the mounting base and the axially extended center through hole of the nail holder and adapted to drive a nail into the workpiece; and at least one magnet mounted inside the nail holder and adapted to attract a nail for enabling the attracted nail to be driven into the workpiece by the hammering rod.